fork download
copy 
  1. #include <iostream>
  2. using namespace std;
  3.  
  4. template<typename T>
  5. class CAutoVar
  6. {
  7. public:
  8.     template<typename TVar>
  9.     class var
  10.     {         
  11.     public:
  12.         var(CAutoVar<TVar> &handler, TVar &var) : m_Handler(handler), m_Var(var) {};
  13.         ~var() 
  14.         { 
  15.             m_Handler.check(); 
  16.         }
  17.         operator TVar&() { return m_Var; }
  18.  
  19.     private:
  20.         TVar &m_Var;
  21.         CAutoVar<TVar> &m_Handler;
  22.     };
  23.  
  24.     typedef var<T> var_type;
  25.  
  26.     CAutoVar(T rhs = T());
  27.     operator var_type();
  28.     T& operator=(T &rhs);
  29.  
  30. private:
  31.     void check();
  32.  
  33. private:
  34.     T   m_Var;
  35. };
  36.  
  37. template<typename T>
  38. void CAutoVar<T>::check()
  39. {
  40.     printf("checked %d\n", m_Var);
  41. }
  42.  
  43. template<typename T>
  44. CAutoVar<T>::CAutoVar(T rhs)
  45.     : m_Var(rhs)
  46. {
  47. }
  48.  
  49. template<typename T>
  50. CAutoVar<T>::operator var_type()
  51. {
  52.     return var_type(*this, m_Var);
  53. }
  54.  
  55. template<typename T>
  56. T &CAutoVar<T>::operator=(T &rhs)
  57. {
  58.     m_Var = rhs;
  59.     return m_Var;
  60. }
  61.  
  62.  
  63. int main()
  64. {
  65.     CAutoVar<int> n;
  66.     printf("%d\n", n);    // 0
  67.  
  68.     static_cast<CAutoVar<int>::var_type>(n) += 10;
  69.     printf("%d\n", n);    // 10
  70.  
  71.     return 0;
  72. }
  73.  
Success #stdin #stdout 0s 3468KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
0
checked 10
10
https://ideone.com/nKB3bI
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!